Prospective dynamic balance control in healthy children and adults.

Balance control during gait initiation was studied using center of pressure (CoP) data from force plate measurements. Twenty-four participants were divided into four age groups: (1) 2-3 years, (2) 4-5 years, (3) 7-8 years, and (4) adults. Movement in the antero-posterior (CoPy) direction during the initial step was tau-G analyzed, investigating the hypothesis that tau of the CoPy motion-gap (tau(CoPy)), i.e., the time it will take to close the gap at its current closure rate, is tau-coupled onto an intrinsic tau-G guide (tau(G)), by maintaining the relation tau(CoPy )= Ktau(G), for a constant K. Mean percentage of tau-guidance for all groups was >/=99%, resulting in all r(2) exceeding 0.95, justifying an investigation of the regression slope as an estimate of the coupling constant K in the tau-coupling equation. Mean K values decreased significantly with age and were for 2- to 3-year-olds 0.56, for 4- to 5-year-olds 0.50, for 7- to 8-year-olds 0.47, and for adults 0.41. Therefore, the control of dynamic balance develops from the youngest children colliding with the boundaries of the base of support (K > 0.5) to the older children and adults making touch contact (K </= 0.5). The findings may provide us with a measure for testing prospective balance control, a helpful tool in assessing whether a child is following a normal developmental pattern.